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Polarisation de fluorescence des polypeptides portant un groupe terminal fluorescent
Author(s) -
Frey M.,
Weill G.
Publication year - 1967
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1967.360050206
Subject(s) - chemistry , fluorescence , chromophore , solvent , fluorescence anisotropy , rotational diffusion , optical rotation , polarization (electrochemistry) , molecule , dielectric , photochemistry , analytical chemistry (journal) , optics , organic chemistry , biochemistry , physics , membrane , optoelectronics
The polarization of fluorescence of a chromophore chemically bound on the NH 2 end of a poly( L ‐benzyl glutamate) molecule has been studied as a function of temperature, viscosity, and solvent. The relaxation times depend on both the overall rotation of the helix and the local rotation of the endgroup. In m –cresol the endgroup is rigidly bound and the rotational diffusion constant of the molecule is in good agreement with the values obtained by Kerr effect and dielectric relaxation. In other helicogenic solvents (DMF, DCE, etc.) the local rotation is nearly free. In m ‐cresol‐DMF mixtures a sharp decrease of the polarization around a composition of 40% DMF can be interpreted as a change in the freedom of rotation of the endgroup. No discontinuity in the optical rotation is observed in the solvent mixture. The question of how a rapidly rotating endgroup could show an extrinsic Cotton effect as observed by Bloutand Yamaoka for the system Acridine Orange–PBLG in chloroform is then raised. Polarization of fluorescence measurements on this system show a nearly complete freedom of rotation of the dye and OH D measurements show no detectable Cotton effect in the dye absorption band.